The present invention relates to compounds, process for their synthesis, compositions and methods for the treatment of hepatitis C virus (HCV) infection. In particular, the present invention provides novel peptide analogs, pharmaceutical compositions containing such analogs and methods for using these analogs in the treatment of HCV infection. The present invention also provides processes and intermediates for the synthesis of these peptide analogs.
Hepatitis C virus (HCV) is the major etiological agent of post-transfusion and community-acquired non-A non-B hepatitis worldwide. It is estimated that over 150 million people worldwide are infected by the virus. A high percentage of carriers become chronically infected and many progress to chronic liver disease, so-called chronic hepatitis C. This group is in turn at high risk for serious liver disease such as liver cirrhosis, hepatocellular carcinoma and terminal liver disease leading to death. The mechanism by which HCV establishes viral persistence and causes a high rate of chronic liver disease has not been thoroughly elucidated. It is not known how HCV interacts with and evades the host immune system. In addition, the roles of cellular and humoral immune responses in protection against HCV infection and disease have yet to be established. Immunoglobulins have been reported for prophylaxis of transfusion-associated viral hepatitis, however, the Center for Disease Control does not presently recommend immunoglobulins treatment for this purpose. The lack of an effective protective immune response is hampering the development of a vaccine or adequate post-exposure prophylaxis measures, so in the near-term, hopes are firmly pinned on antiviral interventions.
Various clinical studies have been conducted with the goal of identifying pharmaceutical agents capable of effectively treating HCV infection in patients afflicted with chronic hepatitis C. These studies have involved the use of interferon-alpha, alone and in combination with other antiviral agents. Such studies have shown that a substantial number of the participants do not respond to these therapies, and of those that do respond favorably, a large proportion were found to relapse after termination of treatment.
Until recently, interferon (IFN) was the only available therapy of proven benefit approved in the clinic for patients with chronic hepatitis C. However the sustained response rate is low, and interferon treatment also induces severe side-effects (i.e. retinopathy, thyroiditis, acute pancreatitis, depression) that diminish the quality of life of treated patients. Recently, interferon in combination with ribavirin has been approved for patients non-responsive to IFN alone. However, the side effects caused by IFN are not alleviated with this combination therapy.
Therefore, a need exists for the development of effective antiviral agents for treatment of HCV infection that overcomes the limitations of existing pharmaceutical therapies.
HCV is an enveloped positive strand RNA virus in the Flaviviridae family. The single strand HCV RNA genome is approximately 9500 nucleotides in length and has a single open reading frame (ORF) encoding a single large polyprotein of about 3000 amino acids. In infected cells, this polyprotein is cleaved at multiple sites by cellular and viral proteases to produce the structural and non-structural (NS) proteins. In the case of HCV, the generation of mature nonstructural proteins (NS2, NS3, NS4A, NS4B, NS5A, and NS5B) is effected by two viral proteases. The first one, as yet poorly characterized, cleaves at the NS2-NS3 junction; the second one is a serine protease contained within the N-terminal region of NS3 (henceforth referred to as NS3 protease) and mediates all the subsequent cleavages downstream of NS3, both in cis, at the NS3-NS4A cleavage site, and in trans, for the remaining NS4A-NS4B, NS4B-NS5A, NS5A-NS5B sites. The NS4A protein appears to serve multiple functions, acting as a cofactor for the NS3 protease and possibly assisting in the membrane localization of NS3 and other viral replicase components. The complex formation of the NS3 protein with NS4A seems necessary to the processing events, enhancing the proteolytic efficiency at all of the sites. The NS3 protein also exhibits nucleoside triphosphatase and RNA helicase activities. NS5B is a RNA-dependent RNA polymerase that is involved in the replication of HCV.
A general strategy for the development of antiviral agents is to inactivate virally encoded enzymes that are essential for the replication of the virus. In this vein, patent application WO 97/06804 describes the (xe2x88x92) enantiomer of the nucleoside analogue cytosine-1,3-oxathiolane (also known as 3TC) as active against HCV. This compound, although reported as safe in previous clinical trials against HIV and HBV, has yet to be clinically proven active against HCV and its mechanism of action against the virus has yet to be reported.
Intense efforts to discover compounds which inhibit the NS3 protease or RNA helicase of HCV have led to the following disclosures:
U.S. Pat. No. 5,633,388 describes heterocyclic-substituted carboxamides and analogues as being active against HCV. These compounds are directed against the helicase activity of the NS3 protein of the virus but clinical tests have not yet been reported.
A phenanthrenequinone has been reported by Chu et al., (Tet. Lett., (1996), 7229-7232) to have activity against the HCV NS3 protease in vitro. No further development on this compound has been reported.
A paper presented at the Ninth International Conference on Antiviral Research, Urabandai, Fukyshima, Japan (1996) (Antiviral Research, (1996), 30, 1, A23 (abstract 19)) reports thiazolidine derivatives to be inhibitory to the HCV protease.
Several studies have reported compounds inhibitory to other serine proteases, such as human leukocyte elastase. One family of these compounds is reported in WO 95/33764 (Hoechst Marion Roussel, 1995). The peptides disclosed in this application are morpholinylcarbonyl-benzoyl-peptide analogues that are structurally different from the peptides of the present invention.
WO 98/17679 from Vertex Pharmaceuticals Inc. discloses inhibitors of serine protease, particularly, Hepatitis C virus NS3 protease. These inhibitors are peptide analogues based on the NS5A/5B natural substrate. Although several tripeptides are disclosed, all of these peptide analogues contain C-terminal activated carbonyl function as an essential feature. These analogues were also reported to be active against other serine protease and are therefore not specific for HCV NS3 protease.
Hoffman LaRoche has also reported hexapeptides that are proteinase inhibitors useful as antiviral agents for the treatment of HCV infection. These peptides contain an aldehyde or a boronic acid at the C-terminus.
Steinkahler et al. and Ingallinella et al. have published on NS4A-4B product inhibition (Biochemistry (1998), 37, 8899-8905 and 8906-8914). However, the peptides and peptide analogues presented do not include nor do they lead to the design of the peptides of the present invention.
One advantage of the present invention is that it provides tripeptides that are inhibitory to the NS3 protease of the hepatitis C virus.
A further advantage of one aspect of the present invention resides in the fact that these peptides specifically inhibit the NS3 protease and do not show significant inhibitory activity at concentrations up to 300 xcexcM against other serine proteases such as human leukocyte elastase (HLE), porcine pancreatic elastase (PPE), or bovine pancreatic chymotrypsin, or cysteine proteases such as human liver cathepsin B (Cat B).
A further advantage of the present invention is that it provides small peptides of low molecular weight that may be capable of penetrating cell membranes and may be active in cell culture and in vivo with good pharmacokinetic profile.
Included in the scope of the invention are racemates, diastereoisomers and optical isomers of a compound of formula (I): 
wherein
B is H, a C6 or C10 aryl, C7-16 aralkyl; Het or (lower alkyl)-Het, all of which optionally substituted with C1-6 alkyl; C1-6 alkoxy; C1-6 alkanoyl; hydroxy; hydroxyalkyl; halo; haloalkyl; nitro; cyano; cyanoalkyl; amino optionally substituted with C1-6 alkyl; amido; or (lower alkyl)amide;
or B is an acyl derivative of formula R4xe2x80x94C(O)xe2x80x94; a carboxyl of formula R4xe2x80x94Oxe2x80x94C(O)xe2x80x94; an amide of formula R4xe2x80x94N(R5)xe2x80x94C(O)xe2x80x94; a thioamide of formula R4xe2x80x94N(R5)xe2x80x94C(S)xe2x80x94; or a sulfonyl of formula R4xe2x80x94SO2 wherein
R4 is
(i) C1-10 alkyl optionally substituted with carboxyl, C1-6 alkanoyl, hydroxy, C1-6 alkoxy, amino optionally mono- or di-substituted with C1-6 alkyl, amido, or (lower alkyl) amide;
(ii) C3-7 cycloalkyl, C3-7 cycloalkoxy, or C4-10 alkylcycloalkyl, all optionally substituted with hydroxy, carboxyl, (C1-6 alkoxy)carbonyl, amino optionally mono- or di-substituted with C1-6 alkyl, amido, or (lower alkyl) amide;
(iii) amino optionally mono- or di-substituted with C1-6 alkyl; amido; or (lower alkyl)amide;
(iv) C6 or C10 aryl or C7-16 aralkyl, all optionally substituted with C1-6 alkyl, hydroxy, amido, (lower alkyl)amide, or amino optionally mono- or di-substituted with C16 alkyl; or
(v) Het or (lower alkyl)-Het, both optionally substituted with C1-6 alkyl, hydroxy, amido, (lower alkyl) amide, or amino optionally mono- or di-substituted with C1-6 alkyl;
R5 is H or C1-6 alkyl;
with the proviso that when R4 is an amide or a thioamide, R4 is not (ii) a cycloalkoxy; and
Y is H or C1-6 alkyl;
R3 is C1-8 alkyl, C3-7 cycloalkyl, or C4-10 alkylcycloalkyl, all optionally substituted with hydroxy, C1-6 alkoxy, C1-6 thioalkyl, amido, (lower alkyl)amido, C6 or C10 aryl, or C7-16 aralkyl;
R2 is CH2xe2x80x94R20, NHxe2x80x94R20, Oxe2x80x94R20 or Sxe2x80x94R20, wherein R20 is a saturated or unsaturated C3-7 cycloalkyl or C4-10(alkylcycloalkyl), all of which being optionally mono-, di- or tri-substituted with R21,
or R20 is a C6 or C10 aryl or C7-14 aralkyl, all optionally mono-, di- or tri-substituted with R21,
or R20 is Het or (lower alkyl)-Het, both optionally mono-, di- or tri-substituted with R21,
wherein each R21 is independently C1-6 alkyl; C1-6 alkoxy; lower thioalkyl; sulfonyl; NO2; OH; SH; halo; haloalkyl; amino optionally mono- or di-substituted with C1-6 alkyl, C6 or C10 aryl, C7-14 aralkyl, Het or (lower alkyl)-Het;
amido optionally mono-substituted with C1-6 alkyl, C6 or C10 aryl, C7-14 aralkyl, Het or (lower alkyl)-Het;
carboxyl; carboxy(lower alkyl); C6 or C10 aryl, C7-14 aralkyl or Het, said aryl, aralkyl or Het being optionally substituted with R22;
wherein R22 is C1-6 alkyl; C3-7 cycloalkyl; C1-6 alkoxy; amino optionally mono- or di-substituted with C1-6 alkyl; sulfonyl; (lower alkyl)sulfonyl; NO2; OH; SH; halo; haloalkyl; carboxyl; amide; (lower alkyl)amide; or Het optionally substituted with C1-6 alkyl
R1 is H, C1-6 alkyl, C3-7 cycloalkyl, C2-6 alkenyl, or C2-6 alkynyl, all optionally substituted with halogen;
or a pharmaceutically acceptable salt or ester thereof.
Included within the scope of this invention is a pharmaceutical composition comprising an anti-hepatitis C virally effective amount of a compound of formula I, or a therapeutically acceptable salt or ester thereof, in admixture with a pharmaceutically acceptable carrier medium or auxiliary agent.
An important aspect of the invention involves a method of treating a hepatitis C viral infection in a mammal by administering to the mammal an anti-hepatitis C virally effective amount of the compound of formula I, or a therapeutically acceptable salt or ester thereof or a composition as described above.
Another important aspect involves a method of inhibiting the replication of hepatitis C virus by exposing the virus to a hepatitis C viral NS3 protease inhibiting amount of the compound of formula I, or a therapeutically acceptable salt or ester thereof or a composition as described above.
Still another aspect involves a method of treating a hepatitis C viral infection in a mammal by administering thereto an anti-hepatitis C virally effective amount of a combination of the compound of formula I, or a therapeutically acceptable salt or ester thereof. According to one embodiment, the pharmaceutical compositions of this invention comprise an additional immunomodulatory agent. Examples of additional immunomodulatory agents include but are not limited to, xcex1-, xcex2-, and xcex4-interferons.
Definitions
As used herein, the following definitions apply unless otherwise noted: With reference to the instances where (R) or (S) is used to designate the configuration of a substituent, e.g. R1 of the compound of formula I, the designation is done in the context of the compound and not in the context of the substituent alone.
The natural amino acids, with exception of glycine, contain a chiral carbon atom. Unless otherwise specifically indicated, the compounds containing natural amino acids with the L-configuration are preferred. However, applicants contemplate that when specified, some amino acids of the formula I can be of either D- or L-configuration or can be mixtures of D- and L-isomers, including racemic mixtures. The designation xe2x80x9cP1, P2 and P3xe2x80x9d as used herein refer to the position of the amino acid residues starting from the C-terminus end of the peptide analogues and extending towards the N-terminus [i.e. P1 refers to position 1 from the C-terminus, P2: second position from the C-terminus, etc.) (see Berger A. and Schechter I., Transactions of the Royal Society London series (1970), B257, 249-264].
The abbreviations for the xcex1-amino acids used in this application are set forth in Table A.
As used herein the term xe2x80x9c1-aminocyclopropyl-carboxylic acidxe2x80x9d (Acca) refers to a compound of formula: 
As used herein the term xe2x80x9ctert-butylglycinexe2x80x9d refers to a compound of formula: 
The term xe2x80x9cresiduexe2x80x9d with reference to an amino acid or amino acid derivative means a radical derived from the corresponding xcex1-amino acid by eliminating the hydroxyl of the carboxy group and one hydrogen of the xcex1-amino group. For instance, the terms Gln, Ala, Gly, Ile, Arg, Asp, Phe, Ser, Leu, Cys, Asn, Sar and Tyr represent the xe2x80x9cresiduesxe2x80x9d of L-glutamine, L-alanine, glycine, L-isoleucine, L-arginine, L-aspartic acid, L-phenylalanine, L-serine, L-leucine, L-cysteine, L-asparagine, sarcosine and L-tyrosine, respectively.
The term xe2x80x9cside chainxe2x80x9d with reference to an amino acid or amino acid residue means a group attached to the xcex1-carbon atom of the xcex1-amino acid. For example, the R-group side chain for glycine is hydrogen, for alanine it is methyl, for valine it is isopropyl. For the specific R-groups or side chains of the xcex1-amino acids reference is made to A. L. Lehninger""s text on Biochemistry (see chapter 4).
The term xe2x80x9chaloxe2x80x9d as used herein means a halogen substituent selected from bromo, chloro, fluoro or iodo.
The term xe2x80x9cC1-6 alkylxe2x80x9d or xe2x80x9c(lower)alkylxe2x80x9d as used herein, either alone or in combination with another substituent, means acyclic, straight or branched chain alkyl substituents containing from 1 to six carbon atoms and includes, for example, methyl, ethyl, propyl, butyl, tert-butyl, hexyl, 1-methylethyl, 1-methylpropyl, 2-methylpropyl, 1,1-dimethylethyl.
The term xe2x80x9cC3-7 cycloalkylxe2x80x9d as used herein, either alone or in combination with another substituent, means a cycloalkyl substituent containing from three to seven carbon atoms and includes cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and cycloheptyl. This term also includes xe2x80x9cspiroxe2x80x9d-cyclic group such as spiro-cyclopropyl or spiro-cyclobutyl: 
The term xe2x80x9cunsaturated cycloalkylxe2x80x9d includes, for example, cyclohexenyl: 
The term xe2x80x9cC4-10 (alkylcycloalkyl)xe2x80x9d as used herein means a cycloalkyl radical containing from three to seven carbon atoms linked to an alkyl radical, the linked radicals containing up to ten carbon atoms; for example, cyclopropylmethyl, cyclopentylethyl, cyclohexylmethyl, cyclohexylethyl or cycloheptylethyl.
The term xe2x80x9cC2-10 alkenylxe2x80x9d as used herein, either alone or in combination with another radical, means an alkyl radical as defined above containing from 2 to 10 carbon atoms, and further containing at least one double bond. For example alkenyl includes allyl and vinyl.
The term xe2x80x9cC1-6 alkanoylxe2x80x9d as used herein, either alone or in combination with another radical, means straight or branched 1-oxoalkyl radicals containing one to six carbon atoms and includes formyl, acetyl, 1-oxopropyl (propionyl), 2-methyl-1-oxopropyl, 1-oxohexyl and the like.
The term xe2x80x9cC1-6 alkoxyxe2x80x9d as used herein, either alone or in combination with another radical, means the radical xe2x80x94O(C1-6 alkyl) wherein alkyl is as defined above containing up to six carbon atoms. Alkoxy includes methoxy, ethoxy, propoxy, 1-methylethoxy, butoxy and 1,1-dimethylethoxy. The latter radical is known commonly as tert-butoxy.
The term xe2x80x9cC3-7 cycloalkoxyxe2x80x9d as used herein, either alone or in combination with another radical, means a C3-7 cycloalkyl group linked to an oxygen atom, such as, for example: 
The term xe2x80x9cC6 or C10 arylxe2x80x9d as used herein, either alone or in combination with another radical, means either an aromatic monocyclic group containing 6 carbon atoms or an aromatic bicyclic group containing 10 carbon atoms. For example, aryl includes phenyl, 1-naphthyl or 2-naphthyl.
The term xe2x80x9cC7-16 aralkylxe2x80x9d as used herein, either alone or in combination with another radical, means a C6 or C10 aryl as defined above linked to an alkyl group, wherein alkyl is as defined above containing from 1 to 6 carbon atoms. C7-16 aralkyl includes for example benzyl, butylphenyl, and 1-naphthylmethyl.
The term xe2x80x9camino aralkylxe2x80x9d as used herein, either alone or in combination with another radical, means an amino group substituted with a C7-16 aralkyl group, such as, for example, the amino aralkyl: 
The term xe2x80x9c(lower alkyl)amidexe2x80x9d as used herein, either alone or in combination with another radical, means an amide mono-substituted with a C1-6 alkyl, such as: 
The term xe2x80x9ccarboxy(lower)alkylxe2x80x9d as used herein, either alone or in combination with another radical, means a carboxyl group (COOH) linked through a (lower)alkyl group as defined above and includes for example butyric acid.
The term xe2x80x9cheterocyclexe2x80x9d or xe2x80x9cHetxe2x80x9d as used herein, either alone or in combination with another radical, means a monovalent radical derived by removal of a hydrogen from a five-, six-, or seven-membered saturated or unsaturated (including aromatic) heterocycle containing from one to four heteroatoms selected from nitrogen, oxygen and sulfur. Furthermore, xe2x80x9cHetxe2x80x9d as used herein, means a heterocycle as defined above fused to one or more other cycle, be it a heterocycle or any other cycle. Examples of suitable heterocycles include: pyrrolidine, tetrahydrofuran, thiazolidine, pyrrole, thiophene, diazepine, 1H-imidazole, isoxazole, thiazole, tetrazole, piperidine, 1,4-dioxane, 4-morpholine, pyridine, pyrimidine, thiazolo[4,5-b]-pyridine, quinoline, or indole, or the following heterocycles: 
The term xe2x80x9c(lower alkyl)-Hetxe2x80x9d as used herein, means a heterocyclic radical as defined above linked through a chain or branched alkyl group, wherein alkyl is as defined above containing from 1 to 6 carbon atoms. Examples of (lower alkyl)-Het include: 
The term xe2x80x9cpharmaceutically acceptable esterxe2x80x9d as used herein, either alone or in combination with another substituent, means esters of the compound of formula I in which any of the carboxyl functions of the molecule, but preferably the carboxy terminus, is replaced by an alkoxycarbonyl function: 
in which the R moiety of the ester is selected from alkyl (e.g. methyl, ethyl, n-propyl, t-butyl, n-butyl); alkoxyalkyl (e.g. methoxymethyl); alkoxyacyl (e.g. acetoxymethyl); aralkyl (e.g. benzyl); aryloxyalkyl (e.g. phenoxymethyl); aryl (e.g. phenyl), optionally substituted with halogen, C1-4 alkyl or C1-4 alkoxy. Other suitable prodrug esters can be found in Design of prodrugs, Bundgaard, H. Ed. Elsevier (1985) incorporated herewith by reference. Such pharmaceutically acceptable esters are usually hydrolyzed in vivo when injected in a mammal and transformed into the acid form of the compound of formula I.
With regard to the esters described above, unless otherwise specified, any alkyl moiety present advantageously contains 1 to 16 carbon atoms, particularly 1 to 6 carbon atoms. Any aryl moiety present in such esters advantageously comprises a phenyl group.
In particular the esters may be a C1-16 alkyl ester, an unsubstituted benzyl ester or a benzyl ester substituted with at least one halogen, C1-6 alkyl, C1-6 alkoxy, nitro or trifluoromethyl.
The term xe2x80x9cpharmaceutically acceptable saltxe2x80x9d as used herein includes those derived from pharmaceutically acceptable bases. Examples of suitable bases include choline, ethanolamine and ethylenediamine. Na+, K+, and Ca++ salts are also contemplated to be within the scope of the invention (also see Pharmaceutical salts, Birge, S. M. et al., J. Pharm. Sci., (1977), 66, 1-19, incorporated herein by reference).
Preferred Embodiments
Included within the scope of this invention are compounds of formula I wherein Preferably, B is a C6 or C10 aryl or C7-16 aralkyl, all optionally substituted with C1-6 alkyl, C1-6 alkoxy, C1-6 alkanoyl, hydroxy, hydroxyalkyl, halo, haloalkyl, nitro, cyano, cyanoalkyl, amido, (lower alkyl)amido, or amino optionally substituted with C1-6 alkyl; or
B is preferably Het or (lower alkyl)-Het, all optionally substituted with C1-6 alkyl, C1-6 alkoxy, C1-6 alkanoyl, hydroxy, hydroxyalkyl, halo, haloalkyl, nitro, cyano, cyanoalkyl, amido, (lower alkyl)amido, or amino optionally substituted with C1-6 alkyl.
Alternatively, B is preferably R4xe2x80x94SO2 wherein R4 is preferably C1-6 alkyl; amido; (lower alkyl)amide; C6 or C10 aryl, C7-4 aralkyl or Het, all optionally substituted with C1-6 alkyl.
Alternatively, B is preferably an acyl derivative of formula R4xe2x80x94C(O)xe2x80x94 wherein R4 is preferably
(i) C1-10 alkyl optionally substituted with carboxyl, hydroxy or C1-6 alkoxy, amido, (lower alkyl)amide, or amino optionally mono- or di-substituted with C1-6 alkyl;
(ii) C3-7 cycloalkyl or C4-10 alkylcycloalkyl, both optionally substituted with hydroxy, carboxyl, (C1-6 alkoxy)carbonyl, amido, (lower alkyl)amide, or amino optionally mono- or di-substituted with C1-6 alkyl;
(iv) C6 or C10 aryl or C7-16 aralkyl, all optionally substituted with C1-6 alkyl, hydroxy, amido, (lower alkyl)amide, or amino optionally substituted with C1-6 alkyl;
(v) Het or (lower alkyl)-Het, both optionally substituted with C1-6 alkyl, hydroxy, amino optionally substituted with C1-6 alkyl, amido, (lower alkyl)amide, or amino optionally substituted with C1-6 alkyl.
Alternatively, B is preferably a carboxyl of formula R4xe2x80x94Oxe2x80x94C(O)xe2x80x94, wherein R4 is preferably
(i) C1-10 alkyl optionally substituted with carboxyl, C1-6 alkanoyl, hydroxy, C1-6 alkoxy, amino optionally mono- or di-substituted with C1-6 alkyl, amido or (lower alkyl)amide;
(ii) C3-7 cycloalkyl, C4-10 alkylcycloalkyl, all optionally substituted with carboxyl, (C1-6 alkoxy)carbonyl, amino optionally mono- or di-substituted with C1-6 alkyl, amido or (lower alkyl)amide;
(iv) C6 or C10 aryl or C7-16 aralkyl optionally substituted with C1-6 alkyl, hydroxy, amido, (lower alkyl)amido, or amino optionally mono- or di-substituted with C1-6 alkyl; or
(v) Het or (lower alkyl)-Het, both optionally substituted with C1-6 alkyl, hydroxy, amino optionally mono- or di-substituted with C1-6 alkyl, amido or (lower alkyl)amido.
Alternatively, B is preferably an amide of formula R4xe2x80x94N(R5)xe2x80x94C(O)xe2x80x94 wherein R4 is preferably
(i) C1-10 alkyl optionally substituted with carboxyl, C1-6 alkanoyl, hydroxy, C1-6 alkoxy, amido, (lower alkyl)amido, or amino optionally mono- or di-substituted with C1-6 alkyl;
(ii) C3-7 cycloalkyl or C4-10 alkylcycloalkyl, all optionally substituted with carboxyl, (C1-6 alkoxy)carbonyl, amido, (lower alkyl)amido, or amino optionally mono- or di-substituted with C1-6 alkyl;
(iii) amino optionally mono- or di-substituted with C1-3 alkyl;
(iv) C6 or C10 aryl or C7-16 aralkyl, all optionally substituted with C1-6 alkyl, hydroxy, amido, (lower alkyl)amide, or amino optionally substituted with C1-6 alkyl; or
(v) Het or (lower alkyl)-Het, both optionally substituted with C1-6 alkyl, hydroxy, amino optionally substituted with C1-6 alkyl, amido or (lower alkyl)amide; and
R5 is preferably H or methyl.
Alternatively, B is a preferably thioamide of formula R4xe2x80x94NHxe2x80x94C(S)xe2x80x94; wherein R4 is preferably
(i) C1-10 alkyl optionally substituted with carboxyl, C1-6 alkanoyl or C1-6 alkoxy;
(ii) C3-7 cycloalkyl or C4-10 alkylcycloalkyl, all optionally substituted with carboxyl, (C1-6 alkoxy)carbonyl, amino or amido.
More preferably, B is a C6 or C10 aryl optionally substituted with C1-6 alkyl, C1-6 alkoxy, C1-6 alkanoyl, hydroxy, hydroxyalkyl, halo, haloalkyl, nitro, cyano, cyanoalkyl, amido, (lower alkyl)amide, or amino optionally mono- or di-substituted with C1-6 alkyl, such that B is for example: 
or B is more preferably Het optionally substituted with C1-6 alkyl, C1-6 alkoxy, C1-6 alkanoyl, hydroxy, halo, amido, (lower alkyl)amide, or amino optionally mono- or di-substituted with C1-6 alkyl, such that B is for example: 
Alternatively, B is more preferably R4xe2x80x94SO2 wherein R4 is preferably C6 or C10 aryl, a C7-14 aralkyl or Het all optionally substituted with C1-6 alkyl; amido, (lower alkyl)amide, such that B is, for example: 
Alternatively, B is more preferably an acyl derivative of formula R4xe2x80x94C(O)xe2x80x94 wherein R4 is preferably
(i) C1-10 alkyl optionally substituted with carboxyl, hydroxy or C1-6 alkoxy; or
(ii) C3-7 cycloalkyl or C4-10 alkylcycloalkyl, both optionally substituted with hydroxy, carboxyl, (C1-6 alkoxy)carbonyl, such that B is, for example: 
or R4 is preferably
(iv) C6 or C10 aryl or C7-16 aralkyl, all optionally substituted with C1-6 alkyl, hydroxy, such that B is for example: 
or R4 is preferably
(v) Het optionally substituted with C1-6 alkyl, hydroxy, amido or amino, such that B is for example: 
Alternatively, B is more preferably a carboxyl of formula R4xe2x80x94Oxe2x80x94C(O)xe2x80x94, wherein R4 is preferably
(i) C1-10 alkyl optionally substituted with carboxyl, C1-6 alkanoyl, hydroxy, C1-6 alkoxy or amido, (lower alkyl)amide, amino optionally mono- or di-substituted with C1-6 alkyl;
(ii) C3-7 cycloalkyl, C4-10 alkylcycloalkyl, all optionally substituted with carboxyl, (C1-6 alkoxy)carbonyl, amido, (lower alkyl)amide, amino optionally mono- or di-substituted with C1-6 alkyl, such that B is for example: 
or R4 is preferably
(iv) C6 or C10 aryl or C7-16 aralkyl, all optionally substituted with C1-6 alkyl, hydroxy, amino optionally substituted with C1-6 alkyl; or
(v) Het or (lower alkyl)-Het, both optionally substituted with C1-6 alkyl, hydroxy, amido, or amino optionally mono-substituted with C1-6 alkyl, such that B is for example: 
Alternatively, B is more preferably an amide of formula R4xe2x80x94N(R5)xe2x80x94C(O)xe2x80x94 wherein R4 is preferably
(i) C1-10 alkyl optionally substituted with carboxyl, C1-6 alkanoyl, hydroxy, C1-6 alkoxy, amido, (lower alkyl)amide, amino optionally mono- or di-substituted with C1-6 alkyl;
(ii) C3-7 cycloalkyl or C4-10 alkylcycloalkyl, all optionally substituted with carboxyl, (C1-6 alkoxy)carbonyl, amido, (lower alkyl)amide, amino optionally mono- or di-substituted with C1-6 alkyl; and
R5 is H or methyl, such that B is for example: 
or R4 is preferably
(iii) amino optionally mono- or di-substituted with C1-3 alkyl, such that B is for example: 
or R4 is preferably
(iv) C6 or C10 aryl or C7-16 aralkyl, all optionally substituted with C1-6 alkyl, hydroxy, amino or amido optionally substituted with C1-6 alkyl; or
(v) Het optionally substituted with C1-6 alkyl, hydroxy, amino or amido, such that B is for example: 
Alternatively, B is more preferably a thioamide of formula R4xe2x80x94NHxe2x80x94C(S)xe2x80x94; wherein R4 is preferably
R4 is (i) C1-10 alkyl; or (ii) C3-7 cycloalkyl, such that B is for example: 
Most preferably, B is an amide of formula R4xe2x80x94NHxe2x80x94C(O)xe2x80x94 wherein R4 is preferably
(i) C1-10 alkyl optionally substituted with carboxyl, C1-6 alkanoyl, hydroxy, C1-6 alkoxy amido, (lower alkyl)amide, amino optionally mono- or di-substituted with C1-6 alkyl;
(ii) C3-7 cycloalkyl or C4-10 alkylcycloalkyl, all optionally substituted with carboxyl, (C1-6 alkoxy)carbonyl, amido, (lower alkyl)amide, amino optionally mono- or di-substituted with C1-6 alkyl; 
or R4 is preferably
(iv) C6 or C10 aryl or C7-16 aralkyl optionally substituted with C1-6 alkyl, hydroxy, amino or amido, such that B is for example: 
Even most preferably, B is tert-butoxycarbonyl (Boc) or 
Preferably, Y is H or methyl. More preferably, Y is H.
Preferably, R3 is C1-8 alkyl, C3-7 cycloalkyl, or C4-10 alkylcycloalkyl, all optionally substituted with hydroxy, C1-6 alkoxy, C1-6 thioalkyl, acetamido, C6 or C10 aryl, or C7-16 aralkyl, such that B is for example: 
More preferably, R3 is the side chain of tert-butylglycine (Tbg), Ile, Val, Chg or: 
Most preferably, R3 is the side chain of Tbg, Chg or Val.
Included within the scope of the invention are compounds of formula I wherein, preferably, R2 is Sxe2x80x94R20 or Oxe2x80x94R20 wherein R20 is preferably a C6 or C10 aryl, C7-16 aralkyl, Het or xe2x80x94CH2xe2x80x94Het, all optionally mono-, di- or tri-substituted with R21.
Preferably, R21 is C1-6 alkyl; C1-6 alkoxy; lower thioalkyl; amino or amido optionally mono-or di-substituted with C1-6 alkyl, C6 or C10 aryl, C7-16 aralkyl, Het or (lower alkyl)-Het; NO2; OH; halo; trifluoromethyl; carboxyl; C6 or C10 aryl, C7-16 aralkyl, or Het, said aryl, aralkyl or Het being optionally substituted with R22. More preferably, R21 is C1-6 alkyl; C1-6 alkoxy; amino; di(lower alkyl)amino; (lower alkyl)amide; C6 or C10 aryl, or Het, said aryl or Het being optionally substituted with R22.
Preferably, R22 is C1-6 alkyl; C3-7 cycloalkyl; C1-6 alkoxy; amino; mono- or di-(lower alkyl)amino; (lower alkyl)amide; sulfonylalkyl; NO2; OH; halo; trifluoromethyl; carboxyl or Het. More preferably, R22 is C1-6 alkyl; C3-7 cycloalkyl; C1-6 alkoxy; amino; mono- or di(lower alkyl)amino; amido; (lower alkyl)amide; halo; trifluoromethyl or Het. Most preferably, R22 is C1-6 alkyl; C1-6 alkoxy; halo; amino optionally mono- or di-substituted with lower alkyl; amido; (lower alkyl)amide; or Het. Even most preferably, R22 is methyl; ethyl; isopropyl; tert-butyl; methoxy; chloro; amino optionally mono- or di-substituted with lower alkyl; amido, (lower alkyl)amide; or (lower alkyl) 2-thiazole.
Alternatively, R2 is preferably selected from the group consisting of: 
More preferably, R2 is 1-naphthylmethoxy; 2-naphthylmethoxy; benzyloxy, 1-naphthyloxy; 2-naphthyloxy; or quinolinoxy unsubstituted, mono- or di-substituted with R21 as defined above. Most preferably, R2 is 1-naphtylmethoxy; or quinolinoxy unsubstituted, mono- or di-substituted with R21 as defined above, such that R2 is for example: 
Still, more preferably, R2 is: 
More preferably, R21A is C1-6 alkyl such as isopropyl, tert-butyl or cyclohexyl; C1-6 alkoxy such as methoxy, 
lower thioalkyl such as 
halo such as chloro;
amino optionally mono-substituted with C1-6 alkyl; or C6 or C10 aryl, such that R21A is for example: dimethylamino, Phxe2x80x94N(Me)xe2x80x94;
unsubstituted C6 or C10 aryl, C7-16 aralkyl, such as for example phenyl or 
or R21A is more preferably Het optionally substituted with R22 wherein R22 is C1-6 alkyl, C1-6 alkoxy, amido, (lower alkyl)amide, amino optionally mono- or di-substituted with C1-6 alkyl, or Het, such that R21A is for example: 
Most preferably, R21A is C6, C10 aryl or Het, all optionally substituted with R22 as defined above, such that R21A is for example: 
Even most preferably, R2 is: 
wherein R22A is preferably C1-6 alkyl (such as methyl); C1-6 alkoxy (such as methoxy); or halo (such as chloro); R22B is preferably C1-6 alkyl, amino optionally mono-substituted with C1-6 alkyl, amido, or (lower alkyl)amide; and R21B is preferably C1-6 alkyl, C1-6 alkoxy, amino, di(lower alkyl)amino, (lower alkyl)amide, NO2, OH, halo, trifluoromethyl, or carboxyl. More preferably, R21B is C1-6 alkoxy, or di(lower alkyl)amino. Most preferably, R21B is methoxy.
As described hereinabove the P1 segment of the compounds of formula I is a cyclobutyl or cyclopropyl ring, both optionally substituted with R1.
Preferably, R1 is H, C1-3 alkyl, C3-5 cycloalkyl, or C2-4 alkenyl optionally substituted with halo. More preferably R1 is ethyl, vinyl, cyclopropyl, 1 or 2-bromoethyl or 1 or 2-bromovinyl. Most preferably, R1 is vinyl.
When R1 is not H, then P1 is preferably a cyclopropyl system of formula: 
wherein C1 and C2 each represent an asymmetric carbon atom at positions 1 and 2 of the cyclopropyl ring. Notwithstanding other possible asymmetric centers at other segments of the compounds of formula I, the presence of these two asymmetric centers means that the compounds of formula I can exist as racemic mixtures of diastereoisomers. As illustrated in the examples hereinafter, the racemic mixtures can be prepared and thereafter separated into individual optical isomers, or these optical isomers can be prepared by chiral synthesis.
Hence, the compound of formula I can exist as a racemic mixture of diastereoisomers at carbon 1 but wherein R1 at carbon 2 is orientated syn to the carbonyl at position 1, represented by the radical: 
or the compound of formula I can exist as a racemic mixture of diastereoisomers wherein R1 at position 2 is orientated anti to the carbonyl at position 1, represented by the radical: 
In turn, the racemic mixtures can be separated into individual optical isomers. A most interesting finding of this invention pertains to the addition of a R1 substituent on the carbon 2 as well as the spatial orientation of the P1 segment. The finding concerns the configuration of the asymmetric carbon 1. A preferred embodiment is one wherein R1 is not H and carbon 1 has the R configuration. 
More explicitly, the introduction of a substituent (R1) at C2 has an impact on the potency when R1 is introduced in a way that C1 has the R configuration. For example compounds 901 (1R,2S) and 203 (1R,2R) have activities of 25 and 82 nM respectively. When compared to the unsubstituted cyclopropyl compound 111 (475 nM), a substantial increase in potency is observed. Moreover, as shown for compounds 901 and 203 when carbon 1 has the R configuration, HCV NS3 protease inhibition is further enhanced by the configuration of the substituent R1 (e.g. alkyl or alkylene) at carbon 2 of the cyclopropyl ring, e.g. the compound that possesses R1 xe2x80x9csynxe2x80x9d to the carboxyl has greater potency (25 nM) than the xe2x80x9cantixe2x80x9d enantiomer (82 nM). We can see the effect of the R vs. S configuration at C1 by comparing compounds 801(1R,2S) and its corresponding (1S,2S) isomer which have potencies of 6 nM and  greater than 10 xcexcM respectively, a difference of over 1500 fold!!
Therefore a most preferred compound is an optical isomer having the R1 substituent and the carbonyl in a syn orientation in the following absolute configuration: 
In the case where R1 is ethyl, for example, the asymmetric carbon atoms at positions 1 and 2 have the R,R configuration.
Included within the scope of this invention are compounds of formula I wherein
B is a C6 or C10 aryl or C7-16 aralkyl, all optionally substituted with C1-6 alkyl, C1-6 alkoxy, C1-6 alkanoyl, hydroxy, hydroxyalkyl, halo, haloalkyl, nitro, cyano, cyanoalkyl, amido, (lower alkyl)amido, or amino optionally substituted with C1-6 alkyl; or
Het or (lower alkyl)-Het, all optionally substituted with C1-6 alkyl, C1-6 alkoxy, C1-6 alkanoyl, hydroxy, hydroxyalkyl, halo, haloalkyl, nitro, cyano, cyanoalkyl, amido, (lower alkyl)amido, or amino optionally substituted with C1-6 alkyl, or
B is R4xe2x80x94SO2 wherein R4 is preferably amido; (lower alkyl)amide; C6 or C10 aryl, C7-14 aralkyl or Het, all optionally substituted with C1-6 alkyl, or
B is an acyl derivative of formula R4xe2x80x94C(O)xe2x80x94 wherein R4 is
(i) C1-10 alkyl optionally substituted with carboxyl, hydroxy or C1-6 alkoxy, amido, (lower alkyl)amide, or amino optionally mono- or di-substituted with C1-6 alkyl;
(ii) C3-7 cycloalkyl or C4-10 alkylcycloalkyl, both optionally substituted with hydroxy, carboxyl, (C1-6 alkoxy)carbonyl, amido, (lower alkyl)amide, or amino optionally mono- or di-substituted with C1-6 alkyl;
(iv) C6 or C10 aryl or C7-16 aralkyl, all optionally substituted with C1-6 alkyl, hydroxy, amido, (lower alkyl)amide, or amino optionally substituted with C1-6 alkyl;
(v) Het or (lower alkyl)-Het, both optionally substituted with C1-6 alkyl, hydroxy, amino optionally substituted with C1-6 alkyl, amido, (lower alkyl)amide, or amino optionally substituted with C1-6 alkyl, or
B is a carboxyl of formula R4xe2x80x94Oxe2x80x94C(O)xe2x80x94, wherein R4 is
(i) C1-10 alkyl optionally substituted with carboxyl, C1-6 alkanoyl, hydroxy, C1-6 alkoxy, amino optionally mono- or di-substituted with C1-6 alkyl, amido or (lower alkyl)amide;
(ii) C3-7 cycloalkyl, C4-10 alkylcycloalkyl, all optionally substituted with carboxyl, (C1-6 alkoxy)carbonyl, amino optionally mono- or di-substituted with C1-6 alkyl, amido or (lower alkyl)amide;
(iv) C6 or C10 aryl or C7-16 aralkyl optionally substituted with C1-6 alkyl, hydroxy, amido, (lower alkyl)amido, or amino optionally mono- or di-substituted with C1-6 alkyl; or
(v) Het or (lower alkyl)-Het, both optionally substituted with C1-6 alkyl, hydroxy, amino optionally mono- or di-substituted with C1-6 alkyl, amido or (lower alkyl)amido, or
B is an amide of formula R4xe2x80x94N(R5)xe2x80x94C(O)xe2x80x94 wherein R4 is
(i) C1-10 alkyl optionally substituted with carboxyl, C1-6 alkanoyl, hydroxy, C1-6 alkoxy, amido, (lower alkyl)amido, or amino optionally mono- or di-substituted with C1-6 alkyl;
(ii) C3-7 cycloalkyl or C4-10 alkylcycloalkyl, all optionally substituted with carboxyl, (C1-6 alkoxy)carbonyl, amido, (lower alkyl)amido, or amino optionally mono- or di-substituted with C1-6 alkyl;
(iii) amino optionally mono- or di-substituted with C1-3 alkyl;
(iv) C6 or C10 aryl or C7-16 aralkyl, all optionally substituted with C1-6 alkyl, hydroxy, amido, (lower alkyl)amide, or amino optionally substituted with C1-6 alkyl; or
(v) Het or (lower alkyl)-Het, both optionally substituted with C1-6 alkyl, hydroxy, amino optionally substituted with C1-6 alkyl, amido or (lower alkyl)amide; and
R5 is preferably H or methyl, or
B is thioamide of formula R4xe2x80x94NHxe2x80x94C(S)xe2x80x94; wherein R4 is
(i) C1-10 alkyl optionally substituted with carboxyl, C1-6 alkanoyl or C1-6 alkoxy;
(ii) C3-7 cycloalkyl or C4-10 alkylcycloalkyl, all optionally substituted with carboxyl, (C1-6 alkoxy)carbonyl, amino or amido;
Y is H or methyl;
R3 is C1-8 alkyl, C3-7 cycloalkyl, or C4-10 alkylcycloalkyl, all optionally substituted with hydroxy, C1-6 alkoxy, C1-6 thioalkyl, acetamido, C6 or C10 aryl, or C7-16 aralkyl;
R2 is Sxe2x80x94R20 or Oxe2x80x94R20 wherein R20 is preferably a C6 or C10 aryl, C7-16 aralkyl, Het or xe2x80x94CH2xe2x80x94Het, all optionally mono-, di- or tri-substituted with R21, wherein
R21 is C1-6 alkyl; C1-6 alkoxy; lower thioalkyl; amino or amido optionally mono- or di-substituted with C1-6 alkyl, C6 or C10 aryl, C7-16 aralkyl, Het or (lower alkyl)-Het; NO2; OH; halo; trifluoromethyl; carboxyl; C6 or C10 aryl, C7-16 aralkyl, or Het, said aryl, aralkyl or Het being optionally substituted with R22, wherein
R22 is C1-6 alkyl; C3-7 cycloalkyl; C1-6 alkoxy; amino; mono- or di-(lower alkyl)amino; (lower alkyl)amide; sulfonylalkyl; NO2; OH; halo; trifluoromethyl; carboxyl or Het; or
R2 is selected from the group consisting of: 
or R2 is 1-naphthylmethoxy; 2-naphthylmethoxy; benzyloxy, 1-naphthyloxy; 2-naphthyloxy; or quinolinoxy unsubstituted , mono- or di-substituted with R21 as defined above;
the P1 segment is a cyclobutyl or cyclopropyl ring, both optionally substituted with R1, wherein R1 is H, C1-3 alkyl, C3-5 cycloalkyl, or C2-4 alkenyl optionally substituted with halo, and said R1 at carbon 2 is orientated syn to the carbonyl at position 1, represented by the radical: 
Included within the scope of this invention are compounds of formula I wherein B is a C6 or C10 aryl optionally substituted with C1-6 alkyl, C1-6 alkoxy, C1-6 alkanoyl, hydroxy, hydroxyalkyl, halo, haloalkyl, nitro, cyano, cyanoalkyl, amido, (lower alkyl)amide, or amino optionally mono- or di-substituted with C16 alkyl; or B is Het optionally substituted with C1-6 alkyl, C1-6 alkoxy, C1-6 alkanoyl, hydroxy, halo, amido, (lower alkyl)amide, or amino optionally mono- or di-substituted with C1-6 alkyl; or B is R4xe2x80x94SO2 wherein R4 is C6 or C10 aryl, a C7-14 aralkyl or Het all optionally substituted with C1-6 alkyl; amido, (lower alkyl)amide; or B is an acyl derivative of formula R4xe2x80x94C(O)xe2x80x94 wherein R4 is
(i) C1-10 alkyl optionally substituted with carboxyl, hydroxy or C1-6 alkoxy; or
(ii) C3-7 cycloalkyl or C4-10 alkylcycloalkyl, both optionally substituted with hydroxy, carboxyl, (C1-6 alkoxy)carbonyl; or
(iv) C6 or C10 aryl or C7-16 aralkyl, all optionally substituted with C1-6 alkyl, hydroxy; or
(v) Het optionally substituted with C1-6 alkyl, hydroxy, amido or amino;
or B is a carboxyl of formula R4xe2x80x94Oxe2x80x94C(O)xe2x80x94, wherein R4 is
(i) C1-10 alkyl optionally substituted with carboxyl, C1-6 alkanoyl, hydroxy, C1-6 alkoxy or amido, (lower alkyl)amide, amino optionally mono- or di-substituted with C1-6 alkyl;
(ii) C3-7 cycloalkyl, C4-10 alkylcycloalkyl, all optionally substituted with carboxyl, (C1-6 alkoxy)carbonyl, amido, (lower alkyl)amide, amino optionally mono- or di-substituted with C1-6 alkyl; or
(iv) C6 or C10 aryl or C7-16 aralkyl, all optionally substituted with C1-6 alkyl, hydroxy, amino optionally substituted with C1-6 alkyl; or
(v) Het or (lower alkyl)-Het, both optionally substituted with C1-6 alkyl, hydroxy, amido, or amino optionally mono-substituted with C1-6 alkyl;
or B is an amide of formula R4xe2x80x94N(R5)xe2x80x94C(O)xe2x80x94 wherein R4 is
(i) C1-10 alkyl optionally substituted with carboxyl, C1-6 alkanoyl, hydroxy, C1-6 alkoxy, amido, (lower alkyl)amide, amino optionally mono- or di-substituted with C1 6 alkyl;
(ii) C3-7 cycloalkyl or C4-10 alkylcycloalkyl, all optionally substituted with carboxyl, (C1-6 alkoxy)carbonyl, amido, (lower alkyl)amide, amino optionally mono- or di-substituted with C1-6 alkyl; and R5 is H or methyl; or
R4 is
(iii) amino optionally mono- or di-substituted with C1-3 alkyl; or
(iv) C6 or C10 aryl or C7-16 aralkyl, all optionally substituted with C1-6 alkyl, hydroxy, amino or amido optionally substituted with C1-6 alkyl; or
(v) Het optionally substituted with C1-6 alkyl, hydroxy, amino or amido; or
B is a thioamide of formula R4xe2x80x94NHxe2x80x94C(S)xe2x80x94; wherein R4 is:
(i) C1-10 alkyl; or (ii) C3-7 cycloalkyl; or
B is an amide of formula R4xe2x80x94NHxe2x80x94C(O)xe2x80x94 wherein R4 is
(i) C1-10 alkyl optionally substituted with carboxyl, C1-6 alkanoyl, hydroxy, C1-6 alkoxy amido, (lower alkyl)amide, amino optionally mono- or di-substituted with C1-6 alkyl;
(ii) C3-7 cycloalkyl or C4-10 alkylcycloalkyl, all optionally substituted with carboxyl, (C1-6 alkoxy)carbonyl, amido, (lower alkyl)amide, amino optionally mono- or di-substituted with C1-6 alkyl;
(iv) C6 or C1-10 aryl or C7-16 aralkyl optionally substituted with C1-6 alkyl, hydroxy, amino or amido;
Y is H.;
R3 is the side chain of tert-butylglycine (Tbg), Ile, Val, Chg or: 
R2 is 1-naphtylmethoxy; or quinolinoxy unsubstituted, mono- or di-substituted with R21 as defined above, or
R2 is: 
xe2x80x83wherein R21A is C1-6 alkyl; C1-6 alkoxy; C6, C10 aryl or Het; lower thioalkyl; halo; amino optionally mono-substituted with C1-6 alkyl; or C6,C10 aryl, C7-16 aralkyl or Het, optionally substituted with R22 wherein R22 is C1-6 alkyl, C1-6 alkoxy, amido, (lower alkyl)amide, amino optionally mono- or di-substituted with C1-6 alkyl, or Het;
P1 is a cyclopropyl ring wherein carbon 1 has the R configuration, 
and R1 is ethyl, vinyl, cyclopropyl, 1 or 2-bromoethyl or 1 or 2-bromovinyl.
Further included in the scope of the invention are compounds of formula I wherein: 
B is tert-butoxycarbonyl (Boc) or
R3 is the side chain of Tbg, Chg or Val;
R2 is: 
xe2x80x83wherein R22A is C1-6 alkyl (such as methyl); C1-6 alkoxy (such as methoxy); or halo (such as chloro); R22B is C1-6 alkyl, amino optionally mono-substituted with C1-6 alkyl, amido, or (lower alkyl)amide; and R21B is C1-6 alkyl, C1-6 alkoxy, amino, di(lower alkyl)amino, (lower alkyl)amide, NO2, OH, halo, trifluoromethyl, or carboxyl;
and P1 is: 
Finally, included within the scope of this invention is each compound of formula I as presented in Tables 1 to 10.
According to an alternate embodiment, the pharmaceutical compositions of this invention may additionally comprise another anti-HCV agent. Examples of anti-HCV agents include, xcex1- or xcex2-interferon, ribavirin and amantadine.
According to another alternate embodiment, the pharmaceutical compositions of this invention may additionally comprise other inhibitors of HCV protease.
According to yet another alternate embodiment, the pharmaceutical compositions of this invention may additionally comprise an inhibitor of other targets in the HCV life cycle, including but not limited to, helicase, polymerase, metalloprotease or internal ribosome entry site (IRES).
The pharmaceutical compositions of this invention may be administered orally, parenterally or via an implanted reservoir. Oral administration or administration by injection is preferred. The pharmaceutical compositions of this invention may contain any conventional non-toxic pharmaceutically-acceptable carriers, adjuvants or vehicles. In some cases, the pH of the formulation may be adjusted with pharmaceutically acceptable acids, bases or buffers to enhance the stability of the formulated compound or its delivery form. The term parenteral as used herein includes subcutaneous, intracutaneous, intravenous, intramuscular, intra-articular, intrasynovial, intrasternal, intrathecal, and intralesional injection or infusion techniques.
The pharmaceutical compositions may be in the form of a sterile injectable preparation, for example, as a sterile injectable aqueous or oleaginous suspension. This suspension may be formulated according to techniques known in the art using suitable dispersing or wetting agents (such as, for example Tween 80) and suspending agents.
The pharmaceutical compositions of this invention may be orally administered in any orally acceptable dosage form including, but not limited to, capsules, tablets, and aqueous suspensions and solutions. In the case of tablets for oral use, carriers which are commonly used include lactose and corn starch. Lubricating agents, such as magnesium stearate, are also typically added. For oral administration in a capsule form, useful diluents include lactose and dried corn starch. When aqueous suspensions are administered orally, the active ingredient is combined with emulsifying and suspending agents. If desired, certain sweetening and/or flavoring and/or coloring agents may be added.
Other suitable vehicles or carriers for the above noted formulations and compositions can be found in standard pharmaceutical texts, e.g. in xe2x80x9cRemington""s Pharmaceutical Sciencesxe2x80x9d, The Science and Practice of Pharmacy, 19th Ed. Mack Publishing Company, Easton, Pa., (1995).
Dosage levels of between about 0.01 and about 100 mg/kg body weight per day, preferably between about 0.5 and about 75 mg/kg body weight per day of the protease inhibitor compounds described herein are useful in a monotherapy for the prevention and treatment of HCV mediated disease. Typically, the pharmaceutical compositions of this invention will be administered from about 1 to about 5 times per day or alternatively, as a continuous infusion. Such administration can be used as a chronic or acute therapy. The amount of active ingredient that may be combined with the carrier materials to produce a single dosage form will vary depending upon the host treated and the particular mode of administration. A typical preparation will contain from about 5% to about 95% active compound (w/w). Preferably, such preparations contain from about 20% to about 80% active compound.
As the skilled artisan will appreciate, lower or higher doses than those recited above may be required. Specific dosage and treatment regimens for any particular patient will depend upon a variety of factors, including the activity of the specific compound employed, the age, body weight, general health status, sex, diet, time of administration, rate of excretion, drug combination, the severity and course of the infection, the patient""s disposition to the infection and the judgment of the treating physician. Generally, treatment is initiated with small dosages substantially less than the optimum dose of the peptide. Thereafter, the dosage is increased by small increments until the optimum effect under the circumstances is reached. In general, the compound is most desirably administered at a concentration level that will generally afford antivirally effective results without causing any harmful or deleterious side effects.
When the compositions of this invention comprise a combination of a compound of formula I and one or more additional therapeutic or prophylactic agent, both the compound and the additional agent should be present at dosage levels of between about 10 to 100%, and more preferably between about 10 and 80% of the dosage normally administered in a monotherapy regimen.
When these compounds or their pharmaceutically acceptable salts are formulated together with a pharmaceutically acceptable carrier, the resulting composition may be administered in vivo to manimals, such as man, to inhibit HCV NS3 protease or to treat or prevent HCV virus infection. Such treatment may also be achieved using the compounds of this invention in combination with agents which include, but are not limited to: immunomodulatory agents, such as xcex1-, xcex2-, or xcex3-interferons; other antiviral agents such as ribavirin, amantadine; other inhibitors of HCV NS3 protease; inhibitors of other targets in the HCV life cycle, which include but not limited to, helicase, polymerase, metalloprotease, or internal ribosome entry site (IRES); or combinations thereof. The additional agents may be combined with the compounds of this invention to create a single dosage form. Alternatively these additional agents may be separately administered to a mammal as part of a multiple dosage form.
Accordingly, another embodiment of this invention provides methods of inhibiting HCV NS3 protease activity in mammals by administering a compound of the formula I, wherein the substituents are as defined above.
In a preferred embodiment, these methods are useful in decreasing HCV NS3 protease activity in a mammal. If the pharmaceutical composition comprises only a compound of this invention as the active component, such methods may additionally comprise the step of administering to said mammal an agent selected from an immunomodulatory agent, an antiviral agent, a HCV protease inhibitor, or an inhibitor of other targets in the HCV life cycle such as helicase, polymerase, or metallo protease or IRES. Such additional agent may be administered to the mammal prior to, concurrently with, or following the administration of the compositions of this invention.
In an alternate preferred embodiment, these methods are useful for inhibiting viral replication in a mammal. Such methods are useful in treating or preventing HCV disease. If the pharmaceutical composition comprises only a compound of this invention as the active component, such methods may additionally comprise the step of administering to said mammal an agent selected from an immunomodulatory agent, an antiviral agent, a HCV protease inhibitor, or an inhibitor of other targets in the HCV life cycle. Such additional agent may be administered to the mammal prior to, concurrently with, or following the administration of the composition according to this invention.
The compounds set forth herein may also be used as laboratory reagents. The compounds of this invention may also be used to treat or prevent viral contamination of materials and therefore reduce the risk of viral infection of laboratory or medical personnel or patients who come in contact with such materials (e.g. blood, tissue, surgical instruments and garments, laboratory instruments and garments, and blood collection apparatuses and materials).
The compounds set forth herein may also be used as research reagents. The compounds of this invention may also be used as positive control to validate surrogate cell-based assays or in vitro or in vivo viral replication assays.
Process
The compounds of the present invention were synthesized according to a general process as illustrated in scheme I (wherein CPG is a carboxyl protecting group and APG is an amino protecting group): 
Briefly, the P1, P2, and P3 can be linked by well known peptide coupling techniques. The P1, P2, and P3 groups may be linked together in any order as long as the final compound corresponds to peptides of Formula I. For example, P3 can be linked to P2-P1;
or P1 linked to P3-P2.
Generally, peptides are elongated by deprotecting the xcex1-amino group of the N-terminal residue and coupling the unprotected carboxyl group of the next suitably N-protected amino acid through a peptide linkage using the methods described. This deprotection and coupling procedure is repeated until the desired sequence is obtained. This coupling can be performed with the constituent amino acids in stepwise fashion, as depicted in Scheme I, or by solid phase peptide synthesis according to the method originally described in Merrifield, J. Am. Chem. Soc., (1963), 85, 2149-2154, the disclosure of which is hereby incorporated by reference. Coupling between two amino acids, an amino acid and a peptide, or two peptide fragments can be carried out using standard coupling procedures such as the azide method, mixed carbonic-carboxylic acid anhydride (isobutyl chloroformate) method, carbodiimide (dicyclohexylcarbodiimide, diisopropylcarbodiimide, or water-soluble carbodiimide) method, active ester (p-nitrophenyl ester, N-hydroxysuccinic imido ester) method, Woodward reagent K-method, carbonyldiimidazole method, phosphorus reagents or oxidation-reduction methods. Some of these methods (especially the carbodiimide method) can be enhanced by adding 1-hydroxybenzotriazole. These coupling reactions can be performed in either solution (liquid phase) or solid phase.
More explicitly, the coupling step involves the dehydrative coupling of a free carboxyl of one reactant with the free amino group of the other reactant in the presence of a coupling agent to form a linking amide bond. Descriptions of such coupling agents are found in general textbooks on peptide chemistry, for example, M. Bodanszky, xe2x80x9cPeptide Chemistryxe2x80x9d, 2nd rev ed., Springer-Verlag, Berlin, Germany, (1993). Examples of suitable coupling agents are N,Nxe2x80x2-dicyclohexylcarbodiimide, 1-hydroxybenzotriazole in the presence of N,Nxe2x80x2-dicyclohexylcarbodiimide or N-ethyl-Nxe2x80x2-[(3-dimethylamino)propyl]carbodiimide. A practical and useful coupling agent is the commercially available (benzotriazol-1-yloxy)tris-(dimethylamino)phosphonium hexafluorophosphate, either by itself or in the presence of 1-hydroxybenzotriazole. Another practical and useful coupling agent is commercially available 2-(1H-benzotriazol-1-yl)-N,N,Nxe2x80x2,Nxe2x80x2-tetramethyluronium tetrafluoroborate. Still another practical and useful coupling agent is commercially available O-(7-azabenzotriazol-1-yl)-N,N,Nxe2x80x2,Nxe2x80x2-tetramethyluronium hexafluorophosphate.
The coupling reaction is conducted in an inert solvent, e.g. dichloromethane, acetonitrile or dimethylformamide. An excess of a tertiary amine, e.g. diisopropylethylamine, N-methylmorpholine or N-methylpyrrolidine, is added to maintain the reaction mixture at a pH of about 8. The reaction temperature usually ranges between 0xc2x0 C. and 50xc2x0 C. and the reaction time usually ranges between 15 min and24 h.
When a solid phase synthetic approach is employed, the C-terminal carboxylic acid is attached to an insoluble carrier (usually polystyrene). These insoluble carriers contain a group that will react with the carboxylic group to form a bond that is stable to the elongation conditions but readily cleaved later. Examples of which are: chloro- or bromomethyl resin, hydroxymethyl resin, trytil resin and 2-methoxy-4-alkoxy-benzylaloconol resin.
Many of these resins are commercially available with the desired C-terminal amino acid already incorporated. Alternatively, the amino acid can be incorporated on the solid support by known methods (Wang, S.-S., J. Am. Chem. Soc., (1973), 95, 1328; Atherton, E.; Shepard, R. C. xe2x80x9cSolid-phase peptide synthesis; a practical approachxe2x80x9d IRL Press: Oxford, (1989); 131-148). In addition to the foregoing, other methods of peptide synthesis are described in Stewart and Young, xe2x80x9cSolid Phase Peptide Synthesisxe2x80x9d, 2nd ed., Pierce Chemical Co., Rockford, Ill. (1984); Gross, Meienhofer, Udenfriend, Eds., xe2x80x9cThe Peptides: Analysis, Synthesis, Biologyxe2x80x9d, Vol. 1, 2, 3, 5, and 9, Academic Press, New-York, (1980-1987); Bodansky et al., xe2x80x9cThe Practice of Peptide Synthesisxe2x80x9d Springer-Verlag, New-York (1984), the disclosures of which are hereby incorporated by reference.
The functional groups of the constituent amino acids generally must be protected during the coupling reactions to avoid formation of undesired bonds. The protecting groups that can be used are listed in Greene, xe2x80x9cProtective Groups in Organic Chemistryxe2x80x9d, John Wiley and Sons, New York (1981) and xe2x80x9cThe Peptides: Analysis, Synthesis, Biologyxe2x80x9d, Vol. 3, Academic Press, New York (1981), the disclosures of which are hereby incorporated by reference.
The xcex1-carboxyl group of the C-terminal residue is usually protected as an ester (CPG) that can be cleaved to give the carboxylic acid. Protecting groups that can be used include: 1) alkyl esters such as methyl, trimethylsilylethyl and t-butyl, 2) aralkyl esters such as benzyl and substituted benzyl, or 3) esters that can be cleaved by mild base treatment or mild reductive means such as trichloroethyl and phenacyl esters. The xcex1-amino group of each amino acid to be coupled to the growing peptide chain must be protected (APG). Any protecting group known in the art can be used. Examples of such groups include: 1) acyl groups such as formyl, trifluoroacetyl, phthalyl, and p-toluenesulfonyl; 2) aromatic carbamate groups such as benzyloxycarbonyl (Cbz or Z) and substituted benzyloxycarbonyls, and 9-fluorenylmethyloxycarbonyl (Fmoc); 3) aliphatic carbamate groups such as tert-butyloxycarbonyl (Boc), ethoxycarbonyl, diisopropylmethoxycarbonyl, and allyloxycarbonyl; 4) cyclic alkyl carbamate groups such as cyclopentyloxycarbonyl and adamantyloxycarbonyl; 5) alkyl groups such as triphenylmethyl and benzyl; 6) trialkylsilyl such as trimethylsilyl; and 7) thiol containing groups such as phenylthiocarbonyl and dithiasuccinoyl. The preferred xcex1-amino protecting group is either Boc or Fmoc. Many amino acid derivatives suitably protected for peptide synthesis are commercially available.
The xcex1-amino protecting group of the newly added amino acid residue is cleaved prior to the coupling of the next amino acid. When the Boc group is used, the methods of choice are trifluoroacetic acid, neat or in dichloromethane, or HCl in dioxane or in ethyl acetate. The resulting ammonium salt is then neutralized either prior to the coupling or in situ with basic solutions such as aqueous buffers, or tertiary amines in dichloromethane or acetonitrile or dimethylformamide. When the Fmoc group is used, the reagents of choice are piperidine or substituted piperidine in dimethylformamide, but any secondary amine can be used. The deprotection is carried out at a temperature between 0xc2x0 C. and room temperature (RT) usually 20-22xc2x0 C.
Any of the amino acids having side chain functionalities must be protected during the preparation of the peptide using any of the above-described groups. Those skilled in the art will appreciate that the selection and use of appropriate protecting groups for these side chain functionalities depend upon the amino acid and presence of other protecting groups in the peptide. The selection of such protecting groups is important in that the group must not be removed during the deprotection and coupling of the xcex1-amino group.
For example, when Boc is used as the xcex1-amino protecting group, the following side chain protecting group are suitable: p-toluenesulfonyl (tosyl) moieties can be used to protect the amino side chain of amino acids such as Lys and Arg; acetamidomethyl, benzyl (Bn), or t-butylsulfonyl moieties can be used to protect the sulfide containing side chain of cysteine; benzyl (Bn) ethers can be used to protect the hydroxy containing side chains of serine, threonine or hydroxyproline; and benzyl esters can be used to protect the carboxy containing side chains of aspartic acid and glutamic acid.
When Fmoc is chosen for the xcex1-amine protection, usually tert-butyl based protecting groups are acceptable. For instance, Boc can be used for lysine and arginine, tert-butyl ether for serine, threonine and hydroxyproline, and tert-butyl ester for aspartic acid and glutamic acid. Triphenylmethyl (Trityl) moiety can be used to protect the sulfide containing side chain of cysteine.
Once the elongation of the peptide is completed all of the protecting groups are removed. When a liquid phase synthesis is used, the protecting groups are removed in whatever manner is dictated by the choice of protecting groups. These procedures are well known to those skilled in the art.
When a solid phase synthesis is used, the peptide is cleaved from the resin simultaneously with the removal of the protecting groups. When the Boc protection method is used in the synthesis, treatment with anhydrous HF containing additives such as dimethyl sulfide, anisole, thioanisole, p-cresol at 0xc2x0 C. is the preferred method for cleaving the peptide from the resin. The cleavage of the peptide can also be accomplished by other acid reagents such as trifluoromethanesulfonic acid/trifluoroacetic acid mixtures. If the Fmoc protection method is used, the N-terminal Fmoc group is cleaved with reagents described earlier. The other protecting groups and the peptide are cleaved from the resin using solution of trifluoroacetic acid and various additives such as anisole, etc.
1. Synthesis of Capping Group B
Different capping groups B are introduced in the following manner:
1.1) When B is an Aryl, Aralkyl: the Arylated Amino Acids were Prepared by One of the Three Methods Below
a) Direct nucleophilic displacement on a fluoro-nitro aryl moiety: 
Briefly, 4-fluoro-3-nitrobenzotrifluoride (a) was reacted with L-amino acid
(b) in the presence of a base such as potassium carbonate at 80xc2x0 C. to yield the desired N-aryl amino acid (c);
b) Copper catalyzed couplings according to Ma et al. (J. Am. Chem. Soc. 1998, 120, 12459-12467): 
Briefly, bromo-4-fluorobenzene (d) was reacted with L-amino acid (b) in the presence of a base such as potassium carbonate and a catalytic amount of copper iodide at 90xc2x0 C. to yield the desired N-aryl amino acid (e); or
c) Nucleophilic displacement of a triflate by an aniline: 
Briefly, o-anisidine (f) was reacted with triflate (g) in the presence of a base such as 2,6-lutidine at 90xc2x0 C. to give benzyl ester (h). Hydrogenation with 10% Pd/C yielded the desired N-aryl amino acid (i).
1.2) When B is an Aminothiazole Derivative 
a) The Fmoc-thiocyanate prepared according to Kearney et al., 1998, J. Org. Chem, 63, 196, was reacted with a protected P3 residue or the whole peptide or a peptide segment to provide the thiourea.
b) The thiourea derivative is reacted with an appropriate bromoketone to provide the corresponding thiazole derivative.
1.3) When B is R4xe2x80x94C(O)xe2x80x94, R4xe2x80x94S(O)2 
Protected P3 or the whole peptide or a peptide segment is coupled to an appropriate acyl chloride or sulfonyl chloride respectively, that is either commercially available or for which the synthesis is well known in the art.
1.4) When B is R4Oxe2x80x94C(O)xe2x80x94
Protected P3 or the whole peptide or a peptide segment is coupled to an appropriate chloroformate that is either commercially available or for which the synthesis is well known in the art. For Boc-derivatives (Boc)2O is used.
For example: 
a) Cyclobutanol is treated with phosgene to furnish the corresponding chloroformate.
b) The chloroformate is treated with the desired NH2-tripeptide in the presence of a base such as triethylamine to afford the cyclobutylcarbamate.
1.5) When B is R4xe2x80x94N(R5).C(O)xe2x80x94, or R4xe2x80x94NHxe2x80x94C(S)xe2x80x94, protected P3 or the whole peptide or a peptide segment is treated with phosgene followed by amine as described in SynLett. Feb 1995; (2); 142-144
2. Synthesis of P2 Moieties
2.1 Synthesis of Precursors
A) Synthesis of Haloarylmethane Derivatives
The preparation of halomethyl-8-quinoline IId was done according to the procedure of K. N. Campbell et al., J. Amer. Chem. Soc., (1946), 68, 1844. 
Briefly, 8-quinoline carboxylic acid IIa was converted to the corresponding alcohol IIc by reduction of the corresponding acyl halide IIb with a reducing agent such as lithium aluminium hydride. Treatment of alcohol IIb with the appropriate hydrohaloacid gives the desired halo derivative IId. A specific embodiments of this process is presented in Example 1.
Synthesis of Aryl Alcohol Derivatives
2-phenyl-4-hydroxyquinoline derivatives IIIc were prepared according to Giardina et al. (J. Med. Chem., (1997), 40, 1794-1807). 
R22 and R21B=alkyl, OH, SH, halo, NH2, NO2.
Briefly, benzoylacetamide (IIIa) was condensed with the appropriate aniline (IIIb) and the imine obtained was cyclized with polyphosphoric acid to give the corresponding 2-phenyl-4-hydroxyquinoline (IIIc). A specific embodiment of this process is presented in Example 2.
Or alternatively, the process can be carried out in a different manner: Benzoylethyl ester (IIIa) was condensed with the appropriate aniline (IIIb) in the presence of acid and the imine obtained was cyclized by heating at 260-280xc2x0 C. to give the corresponding 2-phenyl-4-hydroxyquinoline (IIIc). A specific embodiments of this process is presented in Example 3 (compound 3e).
2.2. Synthesis of P2
A) The synthesis of 4-substituted proline (wherein R2 is attached to the ring via a carbon atom) (with the stereochemistry as shown): 
is done as shown in Scheme IV according to the procedures described by J. Ezquerra et al. (Tetrahedron, (1993), 38, 8665-8678) and C. Pedregal et al. (Tetrahedron Lett., (1994), 35, 2053-2056). 
Briefly, Boc-pyroglutamic acid is protected as a benzyl ester. Treatment with a strong base such as lithium diisopropylamide followed by addition of an alkylating agent (Brxe2x80x94R20 or Ixe2x80x94R20) gives the desired compounds IVe after reduction of the amide and deprotection of the ester.
B) The synthesis of O-substituted-4-(R)-hydroxyproline: 
may be carried out using the different processes described below.
1) When R20 is aryl, aralkyl, Het or (lower alkyl)-Het, the process can be carried out according to the procedure described by E. M. Smith et al. (J. Med. Chem. (1988), 31, 875-885). Briefly, commercially available Boc-4(R)-hydroxyproline is treated with a base such as sodium hydride or potassium tert-butoxide and the resulting alkoxide reacted with halo-R20 (Brxe2x80x94R20, Ixe2x80x94R20, etc.) to give the desired compounds. Specific embodiments of this process are presented in Examples 4, 5 and 7.
2) Alternatively, when R20 is aryl or Het, the compounds can also be prepared via a Mitsunobu reaction (Mitsunobu (1981), Synthesis, January, 1-28; Rano et al., (1995), Tet. Lett. 36(22), 3779-3792; Krchnak et al., (1995), Tet. Lett. 36(5), 62193-6196; Richter et al., (1994), Tet. Lett. 35(27), 4705-4706).
Briefly, commercially available Boc-4(S)-hydroxyproline methyl ester is treated with the appropriate aryl alcohol or thiol in the presence of triphenylphosphine and diethylazodicarboxylate (DEAD) and the resulting ester is hydrolyzed to the acid. Specific embodiments of this process are presented in Examples 6 and 8. 
Alternatively, the Mitsunobu reaction can be carried out in solid phase (Scheme V). The 96-well block of the Model 396 synthesizer (advanced ChemTech) is provided with aliquots of resin-bound compound (Va) and a variety of aryl alcohols or thiols and appropriate reagents are added. After incubation, each resin-bound product (Vb) is washed, dried, and cleaved from the resin.
A Suzuki reaction (Miyaura et al., (1981), Synth. Comm. 11, 513; Sato et al., (1989), Chem. Lett., 1405; Watanabe et al., (1992), Synlett., 207; Takayuki et al., (1993), J. Org. Chem. 58, 2201; Frenette et al., (1994), Tet. Lett. 35(49), 9177-9180; Guiles et al., (1996), J. Org. Chem. 61, 5169-5171) can also be used to further functionalize the aryl substituent.
3. Synthesis of P1 Moieties
3.1 Synthesis of the 4 Possible Isomers of 2-substituted 1-aminocyclopropyl Carboxylic Acid
The synthesis was done according to scheme VI. 
a) Briefly, di-protected malonate VIa and 1,2-dihaloalkane VIb or cyclic sulfate VIc (synthesized according to K. Burgess and Chun-Yen KE (Synthesis, (1996), 1463-1467) are reacted under basic conditions to give the diester VId.
b) A regioselective hydrolysis of the less hindered ester is performed to give the acid VIe.
c) This acid VIe is subjected to a Curtius rearrangement to give a racemic mixture of 1-aminocyclopropylcarboxylic acid derivatives VIf with R1 being syn to the carboxyl group. A specific embodiment for this synthesis is presented in Example 9.
d, e) Alternatively, selective ester formation from the acid VIe with an appropriate halide (P*Cl) or alcohol (P*OH) forms diester VIg in which the P* ester is compatible with the selective hydrolysis of the P ester. Hydrolysis of P ester provides acid VIh.
f) A Curtius rearrangement on VIh gives a racemic mixture of 1-aminocyclopropylcarboxylic acid derivatives VIi with R1 group being anti to the carboxyl group. A specific embodiment for this synthesis is presented in Example 14.
An alternative synthesis for the preparation of derivatives VIIf (when R1 is vinyl and syn to the carboxyl group) is described below. 
Treatment of commercially available or easily obtainable imines VIIa with 1,4-dihalobutene VIIb in presence of a base produces, after hydrolysis of the resulting imine VIIc, VIId having the allyl substituent syn to the carboxyl group. Specific embodiments of this process are presented in Example 15 and 19.
Resolution of all of the above enantiomeric mixtures at carbon 1 (VIe and VIId) can be carried out via:
1) enzymatic separation (Examples 13, 17 and 20);
2) crystallization with a chiral acid (Example 18); or
3) chemical derivatization (Example 10).
Following resolution, determination of the absolute stereochemistry can be carried out as presented in Example 11.
Enantiomeric resolution and stereochemistry determination can be carried out in the same manner for the enantiomeric mixtures at carbon 1 wherein the substituent at C2 is anti to the carboxyl group (VIi).
3.2 Synthesis of 1-aminocyclobutyl Carboxylic Acid
The synthesis of 1,1-aminocyclobutanecarboxylic acid is carried out according to xe2x80x9cKavin Douglas; Ramaligam Kondareddiar; Woodard Ronald, Synth. Commun. (1985), 15 (4), 267-72. 
Briefly, treatment of compound VIIIa with a base in the presence of VIIIb gives the corresponding cyclobutyl derivative VIIIc. Hydrolysis of the isocyanate and ester groups of VIIIc under acidic conditions (HCl) yields the hydrochloride salt of the 1-amino-cyclobutylcarboxylic acid VIIId. The carboxylic acid is later esterified under methanol in HCl. A specific embodiment of this esterification is described in Example 21.
3.3 Synthesis of 2-substituted 1-aminocyclobutyl Carboxylic Acid 
a) A protected glycine ester derivative such as imine IXa is alkylated with an homoallylic electrophile IXb using an appropriate base such as a metal hydride, hydroxide or alkoxide. Useful leaving groups in IXb include halogens (X=Cl, Br, I) or sulfonate esters (mesylate, tosylate or triflate). The allylic alcohol functionality in IXb is protected with hydroxyl protecting groups well known in the art (e.g. acetate, silyl, acetals).
b) In a second step, the hydroxyl function of monoalkylated derivative IXc is de-protected and converted to a suitable electrophilic function X such as described above for compound IXb.
c) Cyclization of IXd to cyclobutane derivative IXe is carried out by treatment with a base (metal hydrides, alkoxides), followed by hydrolysis using aqueous mineral acids and neutralization with a mild base. At this stage, syn and anti-isomers of IXe can be separated by flash chromatography.
d) Optionally, the double bond in IXe can also be hydrogenated under standard conditions to yield the corresponding saturated derivative IXf.
The invention further comprises a process for the preparation of a peptide analog of formula (I) wherein P1 is a substituted aminocyclopropyl carboxylic acid residue, comprising the step of:
coupling a peptide selected from the group consisting of: APG-P3-P2; or APG-P2;
with a P1 intermediate of formula: 
wherein R1 is C1-6 alkyl, cycloalkyl or C2-6 alkenyl, all optionally substituted with halogen, CPG is a carboxyl protecting group and APG is an amino protecting group and P3 and P2 are as defined above.
The invention further comprises a process for the preparation of: 1)a serine protease inhibitor peptide analog, or 2) a HCV NS3 protease inhibitor peptide analog, this process comprising the step of:
coupling a (suitably protected) amino acid, peptide or peptide fragment with a P1 intermediate of formula: 
wherein R1 is C1-6 alkyl, C3-7 cycloalkyl or C2-6 alkenyl, all optionally substituted with halogen, and CPG is a carboxyl protecting group.
The invention therefore comprises a process for the preparation of: 1) a protease inhibitor peptide analog, or 2) a serine protease inhibitor peptide analog, this process comprising the step of:
coupling a (suitably protected) amino acid, peptide or peptide fragment with an intermediate of formula: 
wherein CPG is a carboxyl protecting group.
The invention also comprises the use of a P1 intermediate of formula: 
wherein R1 is C1-6 alkyl, cycloalkyl or C2-6 alkenyl, all optionally substituted with halogen, for the preparation of: 1)a serine protease inhibitor peptide analog, or 2) a HCV NS3 protease inhibitor peptide analog.
The invention also comprises the use of an intermediate of formula: 
wherein CPG is a carboxyl protecting group, for the preparation of: 1) a protease inhibitor peptide analog, or 2) a serine protease inhibitor peptide analog.
The invention also comprises the use of a P1 intermediate of formula: 
wherein R1 is C1-6 alkyl, cycloalkyl or C2-6 alkenyl, all optionally substituted with halogen, for the preparation of a compound of formula I as defined above.
Finally, the invention also comprises the use of a proline analog of formula: 
wherein
R21A is C1-6 alkyl; C1-6 alkoxy; lower thioalkyl; halo; amino optionally mono-substituted with C1-6 alkyl; C6, C10 aryl, C7-16 aralkyl or Het, said aryl, aralkyl or Het optionally substituted with R22 wherein R22 is C1-6 alkyl, C1-6 alkoxy, amido, (lower alkyl)amide, amino optionally mono- or di-substituted with C1-6 alkyl, or Het, and
R21B is C1-6 alkyl, C1-6 alkoxy, amino, di(lower alkyl)amino, (lower alkyl)amide, NO2, OH, halo, trifluoromethyl, or carboxyl;
for the synthesis of 1) a serine protease inhibitor peptide analog, 2) a HCV NS3 protease inhibitor peptide analog, or 3) a peptide analog of formula I as defined above.